Gear-cutting machine.



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appliance. medrebruary 5,' 191i. serial no. alam.

I, clear, andexact description, `reference befao ing hadto the accompanying. drawings, in which- V Figure 1v is .asideview of a portion ofa gear cutting machine embodying- 'my inventibn; Fig.` 2 is a view partlyfinfront elevation and partly in vertical vsection of a portion of the-machine shown in Fig. 1;

, Figs. 3 andaare horizontalsections, taken,

.on the line llllll---lllla va continuation of. the right hand end of Fig.

of Fig.y 2Fig. 3*al being 3; Fig. ,4 is a diagrammaticl elevation-showing the relation of theblank, the guides and `the cutter in .the form ofmachine shown in the preceding figures; and Figs. 5..and 6 are similar to Fig. 4, 'but showingtwo different modications.

My invention has relation to gear cutting machines for cutting double helical, or herringbone, gears, and of the general character described and claimed in my Patenti No. 1,022,667, of April 9, 1912. The machine of that patent comprises apair of rotary hobs mounted on separate axes and arranged to act upon a continuously revolving gear blank, with means for feeding', both hobs f ther same direction, in a line substantially parallel to the axis "of the blank. lln the machine of the said patent, in order to pro' duce the4 requiredV angularity of the teeth cut`,'diderential-gear mechanism. was provided, whereby` one of the hobs was driven at` a speed relatively greater `than the peripheral speed fof the,blank, land the other hob was driven at a speed slower than the' peripheral speed of the blank. v llfn my Fatents No. 1,019,350 dated Januaxy 7, 1913, No. 1,067,013 and lio. 1,067,014, ated July 8, 1913, I provided means for obviating this diferential gear mechanism. lln ,Patf ent No. 1,049,350,5this was eiected by .a peculiar arrangement of the hob or cutter driving gears by which the speed of the two hobs or cutters was changed relatively to each other and to the blank by relative movements of certain of the gear elements. 1n Patent No. 1,067,013 the same result was eifected'by a di'erent arrangement of thev `:ny .Fatent'vNot 1,067,014 I ich the' following is a full, @t

have .axes` of the hobs or the axis of the blank.

gearing in which one-member of the gearing was movable axially of the other; and in eectedthis by g1v1ngthehobs `an endwise movement in addition to their feeding movement. f

f. -Mypresentinvention provides a gear-.cute

in which the "angularity of the teethl is Aproduced without necessitating `any change in the speedofthe yto the peripheral speed of the lblank and hobsv or ycutters relatively without the necessity-'for a separate endwise mgma'chine of the same general 'character movement of thehobs` or cutters inladdit'ionto their feeding movement.

To this end my invention 4consists inproviding means wherebythe hobsor cutters are fed ina direction at axis of the blank.

The present invention number of differentembodiments; For-instance, the desired resultcan be obtained by arranging thefeed members which carry the hobs er cutters tomove on guides which the properl degree of arlxhularit `with respect to the axis ofthe bla or t e cutters maybe fed in direct vertical lines and the blank may be supported'with -its axis at an angle to the direction of feed; or 'the angularity may be lproduced by moving the feed slides'at an angle and alsosettin the cutters Aat anl angle to .an angle vto the lis susceptible of a I y `lln Fi s. 1 to 4 inclusive ll have illustrated a machine which` embodies the rst of the above mentioned expedients, vision of means for feeding the hobs or cutters obliquely. ln these figures the numeral 2 designates the frame of the machine having at one end a xed head 3 and at the other end portion another head 4 which is movable toward. and away from the head 3 on suitable guides 5. llntermediate these two heads is the rotary work support. 6

upon which the gear blank 7 to be cut or finished is secured and rotated. 8 and 9- designate two rotary hobs or cutters, 'each of which is fixed to a transverse shaft 10 journaled in suitable bearings 11 on a feed slide 12. One of these feed slides is mounted .upon each of the heads 3 and 4 for lup andl down movement, the two hobs or cutters actingv at diametrically opposite por-` tions of the blank. 'llhe two hobs or cutters are rotated in opposite'directions, the

cutter `8` makingits cut from the top ofthe viz., the pro- 12 are mounted the central clearance Space 7L thereof; and thecutter 9 making its cut downwardly from the lower edge of the clearance space to the bottom of the blank. ,s

The guides 13 blank downwardly to upon which the feed slides are at an angle to the vertical, the degree .of angularity corresponding to the desired yangularity' ofthe teeth to be cut or linished, as show-n in Figs. 2 and 4. Eachhob or cutter is driven by-suitable gear connections, such as the spiral gears 14 between the shafts' 10 andxthe oblique Shaft-.S 15. The Shafts with said headeby 15 may be driven in any suitable manner. I have shown each of them as provided'` with a bevel gear wheeli The shaft 18 may be driven from any suitable source of power. I have indicated a driving, pulley 22 on Ithe rightvhandf'end thereof. The opposite endportion ofthe shaft 18 is connected through a set of change gears 23 with'a longitudinal shaft 24-above the shaft 18 and parallel therewith. The shaft 24 carries a worm 2'5 which -drives a worm wheel 26. attached to the work support 6, and `provides means for 4rotating the blank. -The shaft 24 also carries aworm 27 meshing with a worm wheel 28 on a short transverse shaft 29 carrying a spurwheel 30 which meshes with the spur wheel 31 on another and longer transverse shaft 32. This shaft 32 carries a bevel gear wheel 33 which drives a bevel gear wheel 34 on the lower end of an oblique .threaded or screw shaft 35. lThe shaft 35 ,passes4 through a nut' portion 36 of thel feed slide 12 at the .leftv hand end of the machine., The transverse shaft 32 has loosely mounted thereon another bevel gear wheel 37 adapted to be connected to and disconnected from said shaft through the medium vof a suitable clutch 38. Thebevel gear .wheel37 meshes with a similar wheel 39 on'a longitudinal shaft 40 having a threaded portion 41 which engages a nut .42 on the work supportI 6, and provides means for feeding said support toward and away .fromy the head 3. The shaft 40 yis extended. to the opposite end of themachine, as shown in Fig.,-3; and is there connected through the medium.' of gears 43 and 44 with another vlongitudinal screw shaft 45 which engages .a nut 4 6. on

the movable head 4. In v'iew of the :fact

that when the work support 6 1s moved to' the left, the movable head 4 must be moved endwise twice as far as said support in lorder to bring the two hobs or cutters to the same position with reference to the vertical axis of the blank7, the gears 43 and 44 are so proportioned relatively to each otherandv to the pitch of theyscrew shafts 40 and 45 as to cause the head 4 to move twice as fast asv the work support 6 when the clutch 38 is in gear. The. gear 44 may be provided with a clutch connection 47 with the shaft 45 so that said gear can be thrownout of driving engagement lwith its said shaft when it is desired to move the work support independently of the head 4.

The shaft 32 also carries, at the opposite. side ofthe machine lfrom the gear 31, a bevel gear 48 which drives a bevel gear 49 on a' I longitudinal shaft 50. This shaft 50 is connected through gears 51 to he transverse shaft 52 (Fig. 3a) which, thrugh the bevel gears 53, drives the shaftv35, at the right hand end of the machine.

The operation of the machine is as fo l. lows :v-The gear blank 7 having been secured in placeon the table or support 6, 'the shaft 18 is set lin motion to cause the rotation of the two hobs or cutters. The clutch 38 is then4 operated to movethe blank support 6 towardthe hob y8. The vclutch 47 is then actuated to move the head 4 to bringv the hob 9 into proper cuttingrelation to the blank. The feeding movement of the blank and -of the head 4 relatively to the hob 8 is continued until the required depth of cut is reached. When the required depth of cut is reached the clutch 38 is thrown out of gear. As the twohobs are fed downwardly, said blank and hobs are in the meantime rotated at speeds such as would be imparted if either the blank or the hobs'were rotated by their engagement with each other. In this manner the two sets of' teeth are simultaneously formed. Owing'itfo the fact that the guides 13 have an -angularity with respect to the vertical axis of the blank, lequal to the` angularity ofthe teeth with respect to 4 such axis, it will ,be readilyy seen that both sets of teeth willbe cut at the required, buty aty opposite, angles by the feeding movement of the hobs 'while cutting, without any change in their relative speedsand withouty the necessity for any endwise movement thereof, except the endwise component included in their angular movement. This'A avoids the use of differential or'otherspecial gearing and thereby reduces the possibility of` lost motion with resultant l'inaccuracy in the work.

I have shown have given the entire movement tothe head 4V because this somewhatvsimplies the construction` of the machine and reducesy the number of movable gears -which are required. The only gears which require to the head 3`s`tationary and have moven'lentl relative cto `their `driving -shaittseite one'ofthegears iiand one ofthe are-mann loblique axis and giving the) hobs .or cutters a vertical feedingmovement.4 This is illus- .trated diagrammatically, in i"iF-ig; ,5 in 'which 1vthe" blank-is shownat 54" on the inclined table driven byltherworm gear 56.l 5.7is one of lthe feedingslidesimovable vertically infthe guidesS, -and59 is .one ofthehobs carried on the atransverseshaft 60; f'

lflflig. 6 shows another `modification vin which 'the blank f 6 1 is supported onI a hori- Azontaltable, .as in the form `first' described,

,and the'l feeding slide-62 -works on angular guides'68 yasinthe-.irst form; 'but in which :thehob shafts are atan; oblique langle to the vertical axisiof the blank.' Une ofthe shafts is indicated at 64: in Fig. f6. @ne advantage .of this arrangement is that-it permits of the use of a single-threadedhob incertain cases, where with an arrangement such as shown in Fig. 4. a multiple-threaded hobwouldbe necessary. lFor instance,'in cutting a gear with a thirty degree angle in 'the arrangement lshown in Fig. 4, the hob -would have tohave its cutter at an anglel of thirty degrees toits axis; while with the arrangement shown in Ilig. 6, a. gear having teeth with an angle of thirty degrees could be cut, for instance, with a hob having an angle of ten degrees.

This is due to the actthat in the form brings the cutter-morenearly into `lelisin .with the teeth to be cut,- andto that shown in F ig. 6, the angularity of the hob shaft withl respect to the. axis of the blanlk para extent reduces the leadof the hob.

' It will be noted that in the arrangement shown in Figs. 2 and 4, the teeth produced .are at the same angle asthat of the cutting teeth on the hob; while in Figs. "5 and 6, the

teeth produced ,have 'a greater angle than' that rof the cutting teeth `on the hob. .In each ofzFigs. 5 and 6, the angle of theteeth is equalto the angle of the hob teeth plus the angle' ofinclination of the blank -in Fig. 5 or Yof the guide 63 in Fig. 6.

'It will be understood that the broader` features of my invention are independent of the particular arrangement of gearing, etc., which I have illustrated, and that various changes can be madevin the general construction and arrangement ofthe machine within the scope of the appended claims without departing from my invention.

vWhat I claim is:

1. In a machine for cuttingdouble helical gears, a pair of rotary hobs mounted on separateaxes and arranged to act upon a 'continuously' revolving gear blank, and

gears, a pair .of rotary .hobs mounted onAv separateaxes and arranged to-act upon a continuously revolving gear blank, means for rotating the blank and hobs at speeds- -such as would be imparted if either they .blank or the cutters were rotated byftlieirfv engagement lwith each other, and meansfon:

feedingboth hobs in the same direction and. obliquely v'to the axis of the blank; substantially as described.

3. In a machine for forming double helivcal "gears, two rotary cutters, means for feeding 'said vcutters in the same direction andat an angletofth'e axis of the blank to `becut, andmeans 'for driving both cutters at substantially the same speed; substantially as described.

4. 4In amachine for forming double helical gears, two rotary cutters mounted to act simultaneously upon opposite sides of a Yblank, one of said cutters being arranged to lcut downwardly from one end of the blank toward its center, andthe other to cut from the central portion of the blank downwardly toward its lower edge, and .means for feeding both cutters in-the same direction and at lan angle tothe axis of the said blank; substantially .as described.

5. In a machine for forming double heli-` cal gears, a rotary blank carrier, two toolv -carriers movable in the same directionbut at fan angle -to the axis of the blank to be cut, and a .cutter mounted. on each carrier,

saidcutters being arranged to act simultav 'neous'ly upon diierent portions of the blank; substantially as described.

6. Ina machine for forming doublel helical gears, a rotar-y blankcarrier, two tool carriers movable in the same direction but at an angle to the axis of the blank to be cut, and a cutter mounted on each carrier, lsaid-cutters being arranged to act simultaneously upon diderent portions of the blank, together with means for driving both cutters at substantially the same speed; substantially as described.

7. In .a machine .for forming double helical gears, the combination of a rotary blank support, 'means for rotating said support, two heads arranged at opposite sides of said support, a tool carrier mounted on each of said heads and movable downwardly at an angle to the axis of the blank to be cut, feed'- ing means lfor said tool carriers, tools mounted on the carriers, .and means for rotating both tools at substantially speed; substantially as described.

8. In a machine for forming double helical gears, the combination of a rotary blank Lsupport, means for rotating said support the same v two heads arranged at opposite sides of said support, a tool carrier mounted on eachpof said heads .andmovable downwardly at an angle. to the ,a-Xis o the blank to be cut, Y feeding means for said tool carriers, tools mounted on the carriers, and means for ro- .,tating both tools at substantially the same speed, at least one of said heads being movable toward and away romthe other; substantially as described.

9. In a machine for forming double heli- .,cal"gears, .the combination of a rotary blank support, means for. rotating said support, two heads arranged at opposite sides of said stantially as described.

10.y In a machine for forming double helical gears,- the combination of a rotary blank y support, means for rotating said support,

two heads arranged atopposite sides of said support, a tool carrier mounted on each of saidheads and movable downwardly at an anglel to the axis of the blank to be cut,

feeding means for said tool carriers, tools mounted on the carriers, means for rotating both tools at substantially the same speed, one of said heads being xed and .the other head being movable, and means for moving the work support and the movable head toward and away from the fixed head, said means being arranged to move the movable head approximately' twice as fast as the work support; substantially as described.

1l. In a machine for forming double helical gears, a supporting frame havingtwo heads thereon, one of said heads being fixed and the'other movable, a work support intermediate the two heads, each of said heads having inclined guides, a tool carrier mounted to more on each of said guides, means for actuating both tool carriers, a rotary cutter on each tool carrier, means for rotating both cutters at substantially the same speed, means for rotating the work support, and nilans for movingthe work support and the movable head toward and away from the fixed head; substantially as dcscribed.

In testimony whereof, I have hereunto set my hand.

THOMAS FAWCUS.

Witnesses:

Gro. B. BLEMING, GEO. H. PARMELEE. 

